JSFiddle - React, Tailwind, and code Playground

HTML

<div style="position: relative; width: 500px; height: 500px; background-color: Red;">
    <div id="d" style="position: absolute; width: 100px; left: 0px; height: 100px; top: 0px; cursor: move; border: 1px solid black;" unselectable>a</div>
</div>

CSS

#d{
-moz-user-select: -moz-none;
-khtml-user-select: none;
-webkit-user-select: none;
-ms-user-select: none;
user-select: none;
}

JavaScript

var x = 0;
    var y = 0;

    $("#d").live("mousedown", function () {

        var element = $(this);
        var parent = element.parent();

        $(document).mousemove(function (e) {

            var x_movement = 0;
            var y_movement = 0;

            if (x == e.pageX || x == 0) {
                x = e.pageX;
            } else {
                x_movement = e.pageX - x;
                x = e.pageX;
            }

            if (y == e.pageY || y == 0) {
                y = e.pageY;
            } else {
                y_movement = e.pageY - y;
                y = e.pageY;
            }

            var left = parseFloat(element.css("left")) + x_movement;

            // hold inside left
            if (left <= 0) left = 0;

            // hold inside right
            var max_right = (parseFloat(element.outerWidth()) - parent.width()) * -1;
            if (left >= max_right) left = max_right;

            element.css("left", left);

            var top = parseFloat(element.css("top")) + y_movement;

            // hold inside top
            if (top <= 0) top = 0;

            // hold inside bottom
            var max_bottom = (parseFloat(element.outerHeight()) - parent.height()) * -1;
            if (top >= max_bottom) top = max_bottom;

            element.css("top", top);

            return false;

        });

    });

    $(document).mouseup(function () {
        x = 0;
        y = 0;
        $(document).unbind("mousemove");
    });